#include<bits/stdc++.h>
using namespace std;
struct Sec{
	int l, r;
};
bool cmp(const Sec &a, const Sec &b){
    if(a.r == b.r)
        return a.l < b.l;
    else
        return a.r < b.r;
}
int main()
{
    Sec s[10005];
   	int n, ct = 0, lastR = -1;
   	cin >> n;
	for(int i = 1; i <= n; ++i){
		cin >> s[i].l >> s[i].r;
	}
   	sort(s+1, s+1+n, cmp);
	for(int i = 1; i <= n; ++i){
	    if(s[i].l > lastR){
	       ct++;
           lastR = s[i].r;   
        }
    }
    cout << ct;
    return 0;
}

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